1. Field of the Invention
The present invention relates to an electrode plate for a storage battery and, more particularly, to an electrode plate for a nickel-hydrogen storage battery.
2. Description of the Related Art
Referring to FIG. 4, a conventional electrode plate 1 for a nickel-hydrogen storage battery has a rectangular base plate 2, and a paste 3 containing an active substance, loaded into the base plate 2 and spread by rolling. The base plate 2 is, for example, a nickel-plated porous soft steel plate, such as a mesh, a punched plate or a foam metal plate. When the electrode plate 1 is used as a negative electrode, the paste 3 contains a hydrogen absorbing alloy, a conducting agent, a bonding agent and a dispersing agent. When the electrode plate 1 is used as a positive electrode, the paste 3 contains nickel hydroxide. A collector tab 4 is electrically joined to the base plate 2 so as to extend along the long side of the base plate 2 as shown in FIG. 5. A pair of electrodes similar to this electrode plate 1 and serving respectively as a positive electrode and a negative electrode are wound, for example, in cylindrical shape and are disposed opposite to each other in a battery can, the battery can is filled up with an electrolyte and the open end of the battery can is covered with a cover provided with a safety valve. As is generally known, the respective collecting tabs of the positive electrode plate and the negative electrode plate are connected electrically to external positive and negative terminals, respectively.
When forming the base plate 2 of the foregoing conventional electrode plate 1 for a storage battery by cutting a mesh, a punched plate or a porous plate, burrs are liable to be formed particularly in the four corners and the four sides of the rectangular base plate 2. When a pair of electrode plates formed by using base plates having burrs as positive and negative electrodes are wound in cylindrical shape so as to be opposite to each other, contact pressure in the peripheral part and the corners is high and short circuit occurs due to contact between the burrs of the pair of electrode plates.
Accordingly, it is an object of the present invention to provide an electrode plate for a storage battery, capable of preventing short circuit.
To achieve the object, the present invention provides an electrode plate for a battery including a rectangular, conducting, porous base plate having sides, and a paste containing an active substance and spread over surfaces of the base plate, and filled in hollow spaces in the base plate so as to form layers covering the surfaces of the base plate, in which at least one of corners of the porous base plate is rounded, and the edge of at least one of sides of the porous base plate is rounded in cross section.
The above and other objects, features and advantages of the present invention will become more apparent from the following description taken in connection with the accompanying drawings.